Scientists Discover Two New Species of Bone-Munching Worms in Antarctica

Deep in the icy waters at the bottom of the ocean live some of the strangest creatures known to science. These animals exist in a region where there are few nutrients, scavenging what they can from the dead remains of creatures that fall from the light-filtering waters above. Now, scientists have made a new discovery; they've found two new species of worms that feed on decaying whale skeletons.

Popularly known as "zombie" worms, these bone-munching creatures are some of the weirdest animals to be found. The females normally live on sunken whale carcasses. There, they feed by growing rootlike structures since they lack a digestive tract. The males, in contrast, live like parasites attached to the bodies of the females. There, they essentially act as sperm banks, according to Nature.

The two new species of these worms are known as Osedax antarcticus and Osedax deceptionensis. They were discovered after researchers sank the remains of a Minke whale in addition to planks of wood at two sites on the continental shelf off the West Antarctic Peninsula. After about 14 months on the wooden platforms, the bones were covered with "zombie" worms. The wood itself, though, was untouched.

The researchers also found out a little bit more about the worms themselves. These zombie worms are most closely related to a clade of tiny mud-dwelling creatures that use specialist bacteria to consume chemicals in oxygen-poor sediments.

"Previously research had suggested that Osedax had diverged from groups that inhabited sulphidic hydrothermal vents and cold hydrocarbon seeps," said Adrian Glover from London's Natural History Museum in an interview with BBC News. "But was we added in more taxa and more genetic evidence, it implied that they are more closely related to these mud-dwelling 'beard' worms. And that makes sense that the ancestor should be a sediment-dweller given what we think about the distribution of whale bones on the sea floor."

The findings reveal a little bit more about the evolutionary history of these worms. More specifically, it was once thought that the Antarctic Circumpolar Current acted as a barrier that prevented larvae of many species from reaching Antarctic waters, according to Nature. These latest findings, though, suggest that bone-eating worms crossed this barrier several times during their evolutionary history.

The findings are published in the Proceedings of the Royal Society B: Biological Sciences.